Prestressed rolling mills



Nov. 16, 1965 D. R. HOWARD 3,217,525

PRESTRESSED ROLLING MILLS Filed Nov. 6, 1962 6 Sheets-Sheet 1 INVENTORDAVID Rosam- HOWARD H\s ATTQENEY Nov. 16, 1965 Filed Nov. 6, 1962 D. R.HOWARD PRESTRESSED ROLLING MILLS Hal 6 Sheets-Sheet 2 INVENTQR DAVIDROBERT H OWARD H\S ATTORNEY Nov. 16, 1965' D. R. HOWARD 3, ,5

PRESTRESSED ROLLING MILLS Filed Nov. 6, 1962 6 Sheets-Sheet 3 lNVENT'QRDAVID ROBERT HOWARD H IS ATTORNEY Nov. 16, 1965 Filed NOV. 6, 1962 6Sheets-Sheet 4.

|NVENTOR DAVID ROBERT HOWARD H I S ATTORNEY Nov. 16, 1965 D. R. HOWARD3,217,525

PRESTRES SED ROLLING MILLS Filed Nov. 6, 1962 6 Sheets-Sheet 5 FIG. Z

lNVENTOR DAVID Roaznr HOWAR o H l5 ATTOEINEY Nov. 16, 1965 D. R. HOWARDPRESTRESSED ROLLING MILLS 6 Sheets-Sheet 6 Filed NOV. 6, 1962 INvEN-roRDAVID Roam-r HOWARD H as ATTORNEY United States Patent 3,217,525PRESTRESSED ROLLING MILLS David Robert Howard, Sheffield, England,assignor to Davy and United Engineering Company Limited, Yorkshire,England, a British company Filed Nov. 6, 1962, Ser. No. 235,822 Claimspriority, application Great Britain, Nov. 6, 1%1, 39,611/ 61 Claims.(Cl. 72-237) This invention relates to rolling mills and in particularto means for allowing self-alignment of the roll-neck bearing assemblieswhich are supported by the housing of a rolling mill.

Consider a rolling mill having at least two parallel rolls. Certain ofthese rolls, which are for convenience herein referred to asload-transferring rolls, are designed to transfer the rolling load towhich the mill rolls are subjected when the mill is in use, to thehousing structures of the mill. In the case of a Z-high mill, each ofthe two rolls acts as a load-transferring roll; in the case of a rollingmill with more than two parallel rolls, the outermost rolls are commonlyarranged to act as loadtransferring rolls.

Each load-transferring roll is commonly provided with a pair ofroll-neck bearing assemblies, by which is meant the necks of each suchrolls together with their associated radial-type bearing assemblies. Theroll-neck bearing assemblies are mounted within the housing of therolling mill, and it is through these roll-neck bearing assemblies thatthe rolling load is transferred from the rolls of the mill to thehousing.

When a rolling mill is in use, the rolling load tends to cause theload-transferring rolls to bow. Unless provision is made for theroll-neck bearing assemblies of the load-transferring rolls toself-align, that is to undergo suitable rotational movement inaccordance with the bowing of the load-transferring rolls, bendingmoments are set up in the roll-neck bearing assemblies and the housing.Such bending moments produce a load distribution on the roll-neckbearing assemblies which is non-uniform in an axial direction and whichwill tend to lead to premature failure of the bearing assemblies. Inextreme cases they might also produce fracture of the roll-necks of theloadtransferring rolls.

According to the present invention, in a rolling mill having a housingarranged to support a number of rollneck bearing assemblies the housingis provided with portions which have a relatively low resistance tobending compared with the rest of the housing carrying the rolling load,whereby, when the rolls are subjected to a rolling load relativemovement of different parts of the housing is permitted to take placeabout the said portions of relatively low resistance to bending so as topermit a degree of self-alignment to at least one of the roll-neckbearing assemblies.

The portions of the housing having a relatively low resistance tobending may be of reduced cross-sectional area relative to the remainderof the housing carrying the rolling load.

The housing may comprise two members prestressed together in which casemutually contacting areas of the two members may be located on theportions having a relatively low resistance to bending.

Stop means may be secured to the portions of the housing between whichrelative movement takes place so that after a predetermined degree ofrelative movement, the stop means contact each other, thus olfering agreater degree of resistance to bending and preventing overloading ofthe said portions.

A rolling mill according to the invention may be at 3,217,525 PatentedNov. 16, 1965 least partially supported by means extending from thehousing members in a region of low deflection due to the rolling load,and the said means may be secured to foundation structure in a mannerpermitting a degree of movement of the said means relative to the saidfoundation structure. In this case the said means may comprise twomembers prestressed together, the mutually contacting areas of the saidmembers being of reduced area relative to the cross-sectional area ofthe remainder of the said means carrying the weight of the mill, or partthereof.

Alternatively, a rolling mill according to the invention may be at leastpartially supported by means extending from the housing members in aregion of low resistance to bending, and may comprise means formingupper and lower knife edges engaging with V-shaped slots in a clampmember securing the said means to foundation structure.

Difiiculty is often experienced in obtaining a signal which is a measureof the rolling load to which a rolling mill is subjected. However, sucha signal may be easily obtained in the case of a rolling mill accordingto the invention, which may include measuring means responsive to thesaid relative movement of different parts of the housing structure underthe effect of the rolling load, the measuring means being arranged tosupply a measure of the magnitude of the rolling load, and comprising anextensometer or the like.

The invention, which may be carried into practice in a number of ways,will now be described. with reference to the accompanying drawings ofwhich:

FIGURE 1 is an end elevation of a 4-.high prestressed rolling mill withthe drive arrangements omitted;

FIGURE 2 is a part cross-sectional front elevation, taken along the lineIIII of FIGURE 1;

FIGURE 3 is an enlarged view, taken along the line III-III of FIGURE 2,with the top housing removed;

FIGURE 4 is a view similar to that of FIGURE 1, but showing a modifiedform of the invention and alternative means for supporting the housingstructure;

FIGURE 5 is a view in the direction of the arrow V in FIGURE 4;

FIGURE 6 is an enlarged view along the line VIVI in FIGURE 5 with thetop housing removed;

FIGURE 7 is a view similar to that shown in FIGURES l and 4, showing astill further means of supporting the housing structure, and

FIGURE 8 is a view in the direction of the arrow VIII in FIGURE 7.

Referring to FIGURES 1 and 2: the rolling mill has, at each end, ahousing structure formed in two principle parts, an upper housing member10 and a substantially U-shaped lower housing member 11. The members 10and 11 are prestressed together by means of a pair of prestressing bolts12 which extend through open-sided slots 19 formed in the outer faces ofthe housing members 10 and 11. Each of the bolts 12 is provided at itsupper end with a hydraulic nut 15, and at its lower end with an eye 13by which each bolt is pivotally anchored within the lower housing member11 by a co-operating pin 14. The arrangement is such that when it isrequired to remove the upper housing member 10, the nuts 15 areloosened, whereafter the bolts 12 may be swung out of the slots 19 bypivotal movement about the pins 14.

The upper housing member 10 acts as a chock for an upper backing roll16, whereas the lower housing members 11 is provided with a separatechock 18 to house a lower backing roll 17, the chock 18 being capable ofvertical movement within the lower housing member 11.

The roll gap of the rolling mill can be adjusted by causing the chock 18to move vertically within the lower housing member 11, by rotation of ashaft 24, having 3 oppositely threaded portions 25, upon which areengaged a pair of threaded wedges 26 and 27 which are arranged to engagewith the lower surfaces 18A of the chock 18.

The work rolls of the mill are indicated at 29 and 30, details of thechocks provided for these work rolls being omitted.

Each of the side limbs of the housing members and 11 is provided at itsend with a tapered portion 31. Each tapered portion 31 terminates in atapered contact member 32, which is secured to the tapered portion 31 bymeans of screws 32A, FIGURE 3. The members 32 are provided with ribs 33which engage in corresponding slots formed in the relevant taperedportion 31. The contact members 32 are formed for example, of materialsuch as suitably hardened steel which is capable of withstanding largestresses without permanent deformation. The upper housing member 10 andthe lower housing member 11 thus have two limited areas 34 of mutualcontact.

As described above, the housing members 10 and 11 are prestressedtogether by the bolts 12. However, clearance 35 (FIGURE 1) is providedbetween the bolts and the slots in which they are located to permitrelative movement between the housing members 10 and 11 and the bolts12, as Will be described below.

In the region of the tapered portions 31 of the limbs of the housingmembers 10 and 11, the bolts 12 project out of the slots in which theyare located, as indicated at 36 in FIGURE 2. In this region, the taperedportions 31 of each of the limbs of the lower housing member 11 areprovided, at opposite sides, with stop members 37 which are bolted tothese limbs by means of bolts, the axes of which are indicated at 38.The stop members 37 are provided with cavities 39 through which theportions 36 of the bolts 12 extend, suitable clearances being providedbetween the walls of the cavities 39 and the bolts 12, for the purposeto be described hereinafter.

The roll-neck bearing assemblies for the upper and the lower backingrolls 16 and 17 are indicated respectively at 45 and 46, and arepreferably so arranged that axial movement of the roll-necks of thebacking rolls 16 and 17 can take place, relative to the upper housingmember 10 and the chock 18 respectively.

In operation, the rolls are subjected to the rolling load andconsequently the backing rolls 16 and 17 tend to bow in the direction ofthe arrows 47, FIGURE 2. The roll-neck bearing assemblies 45 and 46transmit the rolling load to the upper housing member 10 and the chock18 respectively and, because of the bowing of the backing rolls 16 and17, the roll-neck bearing assemblies will tend to undergo pivotalmovement in the direction of the arrows 48.

Because of the means provided between the chock 18 and the wedges 26 and27, the lower roll-neck bearing assembly 46 and its associated chock 18are allowed to undergo pivotal movement to allow the roll-neck bearingassembly 46 to self-align.

Furthermore, because of the reduced cross-section of the limbs of thehousing members 10 and 11 in the region of the areas 34 of mutualcontact, the housing structure has a relatively low resistance tobending in these regions. Consequently, the upper housing member 10 ispermitted to undergo pivotal movement in the direction of arrow 48,relative to the lower housing member 11, the regions of the limbs whichare of reduced cross-section acting as hinges, the bending of thehousing structure therefore, being concentrated in these regions. Thisrelative movement permits a degree of self-alignment to the upperrollneck bearing assembly 45.

The areas 34 of mutual contact are made large enough to avoid bucklingof the housing structure under the combined effects of the rolling loadand of the prestressing forces exerted by the bolts 12. The areas 34 arealso chosen, in relation to the magnitude of the prestressing forceexerted by the bolts 12, that when movement of 4- the upper housingmember 10 relative to the lower housing member 11 takes place under theaction of a rolling load, the areas 34 remain fully in contact.

As mentioned above, suitably large clearances 35 are provided betweenthe bolts 12 and the walls of the slots 19 through which the bolts 12extend. Accordingly, the bolts are normally not in contact with thehousing members 10 and 11, except through the medium of the hydraulicnuts 15 bearing upon the housing member 10 and where they are anchoredto the lower housing member 11 by means of the pins 14.

For this reason, the resistance of the bolts 12 to movement of thehousing member 10 relative to the housing member 11 is relatively small,in fact, when the housing members 10 and 11 move under the action of arolling load, the bolts 12 will tend to protrude from the slots 19through which they extend. However, if under the action of a rollingload the bolts 12 were permitted to protrude excessively from theirslots, buckling of the housing structure might take place when largerolling loads are applied. It is for this reason that the stop members37 are provided, the clearances between the bolts 12 and the walls ofthe cavities 39 of the stop members 37, permitting the bolts 12 toprotrude only a limited distance out of the slots 19. If the rollingload becomes larger than a value corresponding to this amount ofrelative movement of the bolts 12 and the housing structure, theportions 36 of bolts 12 come into contact with the stop members 37 sothat effectively the bolts 12 and the housing structure are brought intocontact. The bolts 12 and the housing structure would therefore tend tomove in unison as the rolling load is increased, so reducing thetendency to buckling of the housing structure.

As previously mentioned, in the case of prestressed rolling mills, it isdiflicult to obtain a signal which is a measure of the magnitude of therolling load, to which the rolling mill is subjected. However, such asignal may be obtained by securing an extensometer 53 or the like,between extension arms 52 which extend outwardly from the housingmembers 10 and 11. When relative movement of the housing members 10 and11, takes place under the action of a rolling load, the change in theseparation of the arms 52 will be a measure of the magnitude of therolling load. Consequently, an output signal which is a measure of themagnitude of the rolling load can be obtained from the extensometer 53.

A preferred means of partially supporting a rolling mill (having ahousing structure according to the invention) in a region of lowdeflection due to the rolling load, together with a modified form of thecontact members 32, is shown in FIGURES 4 to 6. Parts of the rollingmill which are common to all the drawings have the same referencenumerals, and will not be further described.

In FIGURES 4 to 6 the side limbs of the housing members do not have thetapered portions 31 of the FIG- URES 1 to 3 embodiment, but the endfaces of the limbs contain slots to receive upper and lower contactingmembers 69 and 70 respectively, which are secured in the slots by bolts,two only of which are shown at 71 in FIGURE 5. The upper contactingmembers 69 are provided with packing pieces 72 for the purpose ofadjustment during assembly and to accommodate changes in roll diameter.The lower contacting members 70 have upwardly extending ridges 70A whichare provided for the purposes of location during assembly. In thisembodiment the stop means for providing additional resistance tobending, after a predetermined relative movement has taken place, maycomprise packing pieces (not shown) inserted between the horizontalfaces of the side limbs of the housing members.

The embodiment shown in FIGURES 4 to 6 also includes tie bars 73 at thefront and the rear of each loadtransferring roll. The longitudinal axesof the tie bars extend parallel with the longitudinal axes of the loadtransferring rolls 1-6 and 17. The longitudinal axes of each pair of tiebars are in a common plane with the longitudinal axis of theirassociated load-transferring roll, and this plane is normal to the planeof the axes of the load transferring rolls.

The tie bars are provided to maintain the centers 74 (FIGURE 2) of theroll-neck bearings at the desired distance apart, and also to furtherthe requirement ideal that movement of the housing members due to therolling load takes place as pivotal movement about the centers 74 of theroll-neck bearing assemblies, as indicated by the arrows 48.

The rolling mill support means above referred to comprise arms 63integral with the lower housing member 11. The arms 63 are provided, attheir lower ends with a removable tapered portion 63A which bears on acradle member 64 secured to a platform structure 65. The arms '63 arealso provided with webs 66, at each side of which are located bolts 67which extend downwardly through open-sided slots formed in the taperedportion 63A and the cradle member 64. The bolts 67 are provided at theirupper ends with nuts 68 and at their lower ends with eyes 67A whichengage pins 67B extending through eyes 69B in lugs 69 secured to theplatform 65.

The arrangement is such that when the lower housing member [[1 isrequired to be removed, the upper housing member is first removed byreleasing the nuts on the prestressing bolts -12, swinging the bolts 12outwardly, that is away from the housing members, by pivotal movementabout the pins 14. The nuts 6-8 upon the upper ends of the bolts 67 arethen released and the bolts 67 are swung outwardly, away from the lowerhousing member 11, by pivotal movement about the pins 67'B.

Referring now to FIGURES 7 and 8 which illustrate a second constructionfor supporting the housing structure, in which the mill is shownpartially supported in the region of the portions of the housingstructure which have a relatively low resistance to bending. Thissupport means comprises knife-edge structures 55, which are ofsubstantially diamond-shaped cross-section, and which form part of andprotrude outwardly from, the lower housing member 11. The knife-edgestructures 55 are supported in cradles 56 which have formed in theirupper surfaces, V-shaped slots 56A which are arranged to receivecorresponding lower V-shaped portions of the knifeedge structures '55.The cradles 56 are secured to a platform structure 60 by bolts, the axesof which are indicated at 5613. Clamp members 57, of which one only isshown in each of the figures, and which have in their lower surfacesinverted V-shaped slots, are arranged to receive the upper V-shapedsurfaces of the knife-edge structures S5. The platform structure '60 issecured to suitable foundations, not shown.

Guide means, in the form of set-screws 62 which extend through uprightmember 61 of the platform 60, are provided to assist in accuratelylocating the lower housing member 1'1 when it is being lowered into theposition as shown in the drawing.

The above-described means of part-supporting the rolling mill, permits adegree of self-alignment to both the upper and lower roll-neck bearingassemblies 45 and 46. It will be appreciated therefore, that with theembodiments shown in FIGURES 4 to 8, when used in conjunction with theembodiment shown in FIGURES 1 to 3, affords the lower roll neck bearingassembly 46 a degree of self-alignment is not required.

It will "be appreciated that when a rolling mill according to theinvention includes a housing which is not prestressed, a degree of localprestressing in the region having a relatively low resistance to bendingis desirable.

It will be further appreciated, that in a rolling mill according to theinvention and having a two-part housing, the two parts of which areprestressed together, the portion or portions of the housing having arelatively low resistance to bending may comprise plates of suitablydimensioned material held in compression between the portions of thehousing. In a further embodiment rollers may be held in compressionbetween arcuate faces on the limbs of the housing members, thuspermitting the housing members some pivotal movement about the rollers.In this case the rollers, in co-operation with the arcuate faces,provide restraint against lateral movement of the housing membersrelative to each other, the lateral restraint in the other embodimentsdescribed being provided by virtue of the friction between the mutuallycontacting faces of the contacting members.

In a further embodiment the stop means may comprise 0 rings of suitablyelastic material located around the bolts 12 so that upon sufficientrelative movement due to the rolling load taking place between the boltsand the housing members, the 0 rings are compressed between the boltsand the housing members, thereby providing an increased degree ofresistance to relative movement of the bolts and the housing members.

In accordance with the provisions of the patent statutes, I haveexplained the principle and operation of my invention and haveillustrated and described what I consider to represent the bestembodiment thereof. However, I desire to have it understood that withinthe scope of the appended claims, the invention may be practicedotherwise than as specifically illustrated and described.

What I claim is:

1. A rolling mill stand comprising a pair of housings, upper and lowerload-transferring horizontal rolls mounted between the housings, upperand lower roll neck bearing assemblies supported in each housing, eachhousing being formed in two parts, means for forcing the upper and lowerpart of each housing towards one another, and means arranged between theupper and. lower part of each housing, said latter means having arelatively low resistance to bending compared with the housings,carrying the rolling load, so as to permit a degree of self alignment ofthe roll neck bearing assemblies of one of the rolls.

2. A rolling mill stand comprising a pair of housings, upper and lowerload-transferring horizontal rolls mounted between the housings, eachhousing being formed in two parts, the lower parts slidably supportingchocks carrying roll neck bearing assemblies for the lower roll and theupper parts carrying roll neck bearing assemblies for the upper roll,means for adjusting the height of the chocks relative to the housings,means for forcing the upper and lower parts of each housing towards oneanother, and means arranged between the upper and lower parts of eachhousing, said latter means having a relatively low resistance to bendingabout an axis parallel to the pass line of the stand, compared with thehousings carrying the rolling load, so as to permit a degree of selfalignment of the upper roll neck bearing assemblies.

3. A rolling mill stand according to claim 2 in which the means having arelatively low resistance to bending are of reduced cross sectional arearelative to the housings carrying the rolling load.

4. A rolling mill according to claim 2 in which the means havingrelatively low resistance to bending are made from material having ahigher limit of elasticity than the housings carrying the rolling load.

5. A rolling mill stand according to claim 2 including stop meansarranged to contact one another after a predetermined degree of relativemovement has taken place between the upper and lower parts of eachhousing, to offer a greater degree of resistance to bending.

6. A rolling mill stand according to claim 2 in which the means having arelatively low resistance to bending comprise contact members detachablefrom the housing parts, said contact members being of subtsantiallytriangular cross section, an apex of the triangle being truncated andthe surface thus formed on each contact member contacting thecorresponding surface of its associated contact member.

7. A rolling mill stand according to claim 2 including tie-bars at thefront and rear of the upper load-transferring roll, inter-connecting thehousings adjacent the roll neck bearings of that roll, the axes of thetie-bars being parallel with, and in horizontal plane through the axisof the upper load-transferring roll.

8. A rolling mill stand according to claim 2 in which the means forforcing the upper and lower parts of each housing together comprisebolts located in slots passing through the housing parts, clearancebeing left between the bolts and the housings sufficient to allowlimited relative movement, and stop means being provided to limit thepivotal movement between the housings and the bolts.

9. A rolling mill stand according to claim 2 including an extensometerconnected between the upper and lower parts of one housing, and arrangedto give a signal indicating the magnitude of the rolling load.

10. A rolling mill stand comprising a pair of housings, upper and lowerload-transferring rolls mounted between the housings, each housing beingformed in two parts, bolts for prestressing the housing parts together,a pair of chocks carrying roll neck bearing assemblies for the lowerroll, means for adjustably supporting the chocks in the lower housingparts respectively, roll neck bearing assemblies for the upper roll, theupper roll neck bearing assemblies being mounted directly in the upperhousing parts in fixed relation relative thereto, bearing means locatedbetween the upper and lower parts of each housing so as to allow limitedpivotal movement of the upper housing parts relative to the lowerhousing parts about axes parallel to the pass-line of the stand, andmeans allowing limited pivotal movement of the lower roll neck bearingassemblies about axes parallel to the pass line of the stand.

11. A rolling mill stand comprising a pair of housings, upper and lowerlad-transferring rolls mounted between the housings, each housing beingformed in two parts, the lower parts slidably supporting chocks carryingroll neck bearing assemblies for the lower roll, and the upper .partshaving roll neck bearing assemblies for the upper roll mounted thereinfixed relation relative thereto, means for forcing the upper and lowerparts of each houslng towards one another, means for adjusting theheight of the checks relative to the housings, means arranged betweenthe upper and lower parts of each housing, said latter means having arelatively low resistance to bending about an axis parallel to the passline of the stand compared with the housings carrying the rolling load,so as to permit a degree of self alignment of the upper roll neckbearing assemblies, the lower parts of each housing being supported on afoundation, and further means arranged between the lower part of eachhousing and'the foundation, said further means having a relatively lowresistance to bending about an axis parallel to the pass line of thestand, so as to permit a degree of self alignment of the lower roll neckbearing assemblies.

12. A rolling mill stand according to claim 11 in which said furthermeans having a relatively low resistance to bending are located betweenmembers extending substantially horizontally from the lower parts of thehousings, at the front and rear of the mill, said members extending fromthe lower housing parts in regions having a low deflection and lowresistance to bending due to the rolling load, and including meanssecuring said members to the foundation structure in a manner permittinga degree of pivotal movement of the lower housing parts relative to thefoundation structure.

. 13. A rolling mill stand according to claim 11 including tie-bars atthe front and rear of each load-transferring roll, each of the tie-barsinter-connecting the housings adjacent the roll neck bearings of itsassociated load transferring roll, the axes of the tie-bars beingparallel with, and adjacent the horizontal planes through, the axes oftheir associated load-transferring rolls.

I 14. A rolling mill stand according to claim 11 including stop meansarranged to limit the pivotal movement of the lower housing partsrelative to the foundation.

15. A rolling mill stand according to claim 11 in which the furthermeans having relatively low resistance to bend ing comprise taperedcontact members, the contact areas of which have reduced cross-sectionalareas relative to the remainder of the means carrying the weight of themill.

References Cited by the Examiner WILLIAM J STEPHENSON, Primary Examiner.

1. A ROLLING MILL STAND COMPRISING A PAIR OF HOUSINGS, UPPER AND LOWERLOAD-TRANSFERRING HORIZONTAL ROLLS MOUNTED BETWEEN THE HOUSINGS, UPPERAND LOWER ROLL NECK BEARING ASSEMBLIES SUPPORTED IN EACH HOUSING, EACHHOUSING BEING FORMED IN TWO PARTS, MEANS FOR FORCING THE UPPER AND LOWERPART OF EACH HOUSING TOWARDS ONE ANOTHER, AND MEANS ARRANGED BETWEEN THEUPPER AND LOWER PART OF EACH HOUSING, SAID LATTER MEANS HAVING ARELATIVELY LOW RESISTANCE TO BENDING COMPARED WITH THE HOUSINGS,CARRYING THE ROLLING LOAD, SO AS TO PERMIT A DEGREE OF SELF ALIGNMENT OFTHE ROLL NECK BEARING ASSEMBLIES OF ONE OF THE ROLLS.